Where can I find AM Activity?

Known AM frequencies in MHz. UK in Bold, European in Italics
 
160 Meters:        1.850 (W. Europe)                       1.977 1.933 1.963 (in the UK)


80 Meters:          3615*, 3625 (in the UK)                     3705** (W. Europe)
                                                               
40 Meters:          7.070*** (Europe)                     7.143 (UK)  

                    
20 Meters:         14.260, 14.330 


15 Meters:         21.285, 21.400 – 21.440 


10 Meters:         29.000-29.200**** 

 
Notes:


*3.615 This is possibly the most popular AM frequency in the UK and the Vintage Military Amateur Radio Society (VMARS) have a regular net every Saturday morning starting at 08:30 UK local time, non members are welcome to call in.

**3.705 Occasional Net from Holland, mainly ex military equipment, run by PI4SRS.


***7.070 Occasional French Net around this frequency.


****29.000 – 29.200 This section of ten meters is used the world over by AM fans, particularly fun working strong Stateside stations when conditions allow.

These commonly used frequencies can be good starting points. As activity grows, expand to other frequencies to prevent congestion and excessively large round tables. As always, PLEASE be considerate of existing QSOs and Nets, and ensure that the frequency is clear before calling “CQ, AM QSO Party”.

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Tips & Tricks for using the AM mode

 

What is AM (Amplitude Modulation)?

AM a voice mode of transmission made up of three parts: A carrier, an upper sideband, and a lower sideband.

AM (the first voice mode,) was once the main voice mode in amateur radio. Now it is a well regarded specialty within the hobby. AM offers a warm, rich audio quality that provides for more personal interaction.

An informative site about AM: http://www.nu9n.com/am.html

Locating and listening to AM transmissions

Locating and listening to an AM signal can be a little bit tricky. When looking for a station that is transmitting in AM it is important to remember that an AM transmission is made up of three parts: a carrier, an upper side band, and a lower side band. The carrier will always be the centre frequency of an AM transmission, with a lower SSB signal AND an upper SSB signal in the same transmitted signal. An AM signal can use a total of 6kcs or more of band space. An important thing to keep in mind when transmitting AM.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A station listening in lower or upper side band can and will hear an AM station just fine, so well that the AM station sounds like it is transmitting on sideband only. This can be confusing, the AM station is transmitting both an upper and a lower sideband but with a center carrier. AM station can not understand any station transmitting in either SSB. A SSB transmission will sound garbled and is unreadable when listening in AM.

How to find AM

The first step in finding AM may be obvious: place the rig in AM, right? Not so simple. The first step is to prepare the receiver. Turn off any noise blankers, band pass filters, notch filters and DSP (Digital Signal Processor) features. These features are great for working SSB and other modes but they can have a negative impact on the quality of the received audio of an AM transmission. Hear the high fidelity that AM provides by turning off all of those sound/signal altering features. Once the receiver is set, the simplest way to find an AM transmission is place the rig in the AM mode and tune the VFO up and down the band, note the garbled signals from SSB transmissions when listening in AM. Eventually a clear voice will emerge and an AM signal has been found. But wait, what frequency is that AM signal on?

Remember an AM transmission is a center carrier and both upper and lower sidebands. It is possible to tune close enough to an AM signal to understand what is being said and be WAY off the centre frequency of the AM transmission. To find the center frequency, place the rig in lower sideband (LSB) mode, and rock the VFO back and forth across the AM transmission. Notice the heterodyne or tone that increases or decrease as you turn the dial? The centre frequency is found when the tone stops (zero beat) and the station transmitting can still be understood clearly.

Now place the rig in upper sideband (USB) and rock the VFO dial again, note the point that the tone or heterodyne stops, it should be the same point or frequency that the heterodyne stopped when listing in LSB. Switch back and forth between LSB and USB just to be sure that the centre frequency has been found. The AM signal should sound clear in either SSB mode. Now switch back to AM and enjoy the high fidelity audio quality that the AM mode supports.

A Word about transmitting in AM

When selecting a frequency to use for an AM transmission, do not forget that the signal transmitted in AM is in many cases at least 6kcs wide (3kc LSB and 3kc USB). Be respectful of operators using other modes and select a frequency that allows plenty of room to prevent interference. Do not forget to allow for the other stations bandwidth.

For example, a LSB QSO on 7.166 will take up 3kcs from 7.163 to 7.166. An AM QSO would have to place their AM center carrier BELOW them on 7.160 using 6kcs of bandwidth from 7.157 to 7.163 or be ABOVE them with the centre carrier on 7.169 using 6kcs from 7.166 to 7.172 in order to prevent interference, although these are fairly ideal numbers and more spacing is typically required.

 

Getting additional help with AM

There are many ways amateur operators can get help, or even just some ideas, for improving the quality of their AM signals. One of the best is to just get in on an AM QSO and ask for suggestions. AMers, like any other operating groups, are thrilled when interest is shown in their mode and many will go out of their way to help.

For more information on using the AM mode, try looking at the AM Fone web pages at:

http://amfone.net/Amforum/index.php

Or you could even join the UK based VMARS (Vintage and Military Amateur Radio Society), who can be found at:

https://www.vmars.org.uk/

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